I just thought I jump in on the post again and let You know how thing turned out.

I checked the things I mentioned in the post and it turned out that my airfilter really needed to be changed. The "funny" thing is that it didn´t look dirty or clogged but when I took it out and shaked it there was this big dust cloud around it full of sand, debris abd dead bugs.

I also advanced the ignition by 5 degrees (from TDC +/- 1 degree to 5 degreea BTDC. This and a new airfilter really impoved things. The car in now much livelier and the response when it needs air is a lot better.